Effect of S-abscisic acid supplementation on the growth performance and antioxidant status of nursery pigs

A total of 320 nursery pigs (DNA 241 × 600; initially 5.4 ± 0.52 kg) were used to evaluate the effect of dietary S-abscisic acid (S-ABA) supplementation on the growth performance and antioxidant status of pigs. Pigs were weaned at approximately 18 d of age and assigned to pens in generalized randomized block design with sex and weight category as blocking factors. Pigs were fed a common phase 1 diet for 7 d postweaning. On d 7 post-weaning, pen of pigs (6.4 ± 0.57 kg) within sex × weight blocks were randomly allotted to 1 of 4 dietary treatments. Treatments included a conventional nursery diet (Control) and 3 diets which used the Control formulation with increasing S-ABA (0.5, 1.0 and 5.0 mg/kg). Treatments were provided during phases 2 (d 0 to 14) and 3 (d 14 to 35). Growth performance was measured weekly. Additionally, 32 pigs on d 0 and 2 pigs per pen on d 14 and 35 were bled to assess the erythrocytes’ total glutathione (GSH + GSSG), reduced glutathione (GSH), oxidized to reduced glutathione ratio (GSSG: GSH), and serum total antioxidant capacity (TAC), superoxide dismutase (SOD), and thiobarbituric acid reactive substances (TBARS). At the termination of the trial, 2 pigs in each pen were euthanized and duodenal, jejunal, and ileal mucosa were collected to measure GSH + GSSG, GSH and GSSG: GSH. No interactive effects between S-ABA and sex on growth performance were observed. Additionally, increasing S-ABA did not influence growth performance. There were also no interactions between S-ABA and collection day on antioxidant parameters. Erythrocyte GSH + GSSG tended to increase (linear, P = 0.056) with increasing S-ABA in the diet on d 14, while GSH tended to increase (linear, P = 0.096) at d 14 and increased up to 1 mg/kg S-ABA (quadratic, P = 0.100) on d 35 with little increase thereafter. The d 35 GSSG: GSH ratio decreased (quadratic, P = 0.022) with increasing S-ABA in the diet. Serum TAC, SOD and TBARS were not influenced by S-ABA in the diet. Similarly, dietary S-ABA had no effect on GSH + GSSG, GSH and GSSG: GSH in the intestinal mucosa. In conclusion, supplementation of S-ABA in the diet reduced the erythrocyte GSSG: GSH ratio without negative effects on growth performance.